The French National Railroad holds the world's speed record for passenger trains in?

The French National Railroad holds the
world's speed record for passenger trains in
regular service. A TGV (tres grand vitesse,
or very great speed) train traveling at a speed
of 325 km/h requires 1.35 km to come to an
emergency stop.
Find the braking acceleration for this train,
assuming constant acceleration. Answer in
units of ms^2.

Well, there are only horizontal components in this question. You are told an initial velocity, a stopping distance, and a final velocity. You are also told that the acceleration is constant, and thus you are indirectly told to use the kinematic equations for constant acceleration. See this webpage for a list of the equations http://hyperphysics.phy-astr.gsu.edu/hbase/mot.html#mot1